Digital photography, a popular pastime, utilizes digital technology to produce digital images. Digital images (or “images”) also can be created, for example, by graphical editing software (e.g., photo editing or drawing software), digital video equipment, and scanners.
After production, an original image (e.g., a photograph) can be processed. Some instances of image processing can produce a new image from an original image. For example, cropping (i.e., extracting a portion of an image) can produce a new image from an original image. Other instances of image processing can ascertain information about an original image without producing a new image. For example, facial-detection processing can determine whether an image depicts one or more faces.
Images can depict visual information using various color models. A color model can describe the way colors are represented, e.g., using one to four values representing color components. For example, in a red-green-blue (RGB) color model, a color can be described using three values—one each for red, green, and blue. Thus, three values can be used to describe the color of each pixel in an RGB image. When an intended interpretation of a color model's components is known, the set of possible colors can be referred to as a color space. For example, the three values associated with an RGB color can be mixed additively to produce a specific color in an RGB color space.